Short of working in a wind tunnel with the wind at your back the ONLY safe way is to wear a respirator, a good one and to have some form of air filtration system working in the shop. I know it's uncomfortable and for those that wear glasses can be a bit of a challenge to find one that will not interfere with them or fog them up however to prove a point that Multifasited has made, get one of those over the ear dust masks and put it on the next time you are cutting and you will be shocked at how much sawdust is generated that you are breathing. Below is just a few of the more common woods we use and the reported side effects of the saw dust.
Pine (Pinus genus) - irritant, runny nose, asthma
Oak (Quercus genus) - irritant, sensitizer, asthma, NPC (Nasopharyngeal carcinoma, or sometimes called nasopharyngeal cancer) (rare)
Birch (Betula genus) - irritant, sensitizer, nausea
Cedar, Aromatic Red - irritant
Douglas-fir - irritant, giddiness, splinters go septic, nausea
Maple (Acer genus) - irritant, sensitizer, asthma; HP ( Severe lung inflammation ) in spalted maple
Travis posted back in 2010 a toxicity list, here is a link to it. http://www.scrollsawvillage.com/topic/5848-wood-toxicity-chart/?hl=%2Bwood+%2Btoxicity+%2Blist
Now not everyone is or will be adversely affected however why take the chance wear a dust mask, a good one if possible when cutting and sanding. I have had 2 friends end up in the hospital with allergic reactions to the sawdust from Yellow Heart since I have asthma I wear a mask and I have a running air filter system in the shop to help keep the floating micro dust contained.
Did I mention that floating micro saw dust can be explosive? In the right conditions a gas water heater, Furnace, space heater could set the floating dust off, not common but possible. Seriously. Just another reason to keep the saw dust under control.
DW